During the past year we have continued our work applying rapid MRI to guide simple and complex mechanical and biological interventions. We have demonstrated direct transthoracic access and closure to the left ventricle using real-time MRI guidance, and found that MRI provides an imaging context that may be a satisfactory alternative to direct surgical exposure. For example, MRI allows appropriate trajectory planning for needle and introducer placement avoiding vital structures, and provides instantaneous evidence of complications such as bleeding allowing for correction. We have demonstrated the limitations of perventricular closure using a commercial collagen vascular plug, which provides satisfactory immediate but not intermediate-term hemostasis. MRI guidance has also afforded the insight that visceral-pericardial separation are required for many approaches to closure of the left ventricular access port, and led to our development of a permissive tamponade procedure during closure. We continue parallel development of two internal designs for closure devices, and have entered into a Collaborative Research and Development Agreement with NeatStitch toward development of their suture-mediated approach. Along a similar vein, we have developed real-time MRI guided perventricular access to the right ventricle to allow device closure of a model muscular ventricular septal defect. Children having small venous access sites may be forced to undergo direct surgical or hybrid surgical-catheter closure of such defects, but real-time MRI allows selection of a suitable trajectory, detection of complications, and successful device closure both of the defect and the perventricular access port. This project required the development of a new non-surgical model of ventricular septal defect using a laser catheter. We have applied active MRI needle catheters for ordinary vascular access procedures in a model of difficult vascular access in swine, which would be an important adjunct to wholly-MRI guided clinical procedures. We have used our facilities to explore procedures that are not necessarily guided by MRI. We have begun to develop a novel approach to percutaneous pulmonary thrombectomy for massive pulmonary embolism. To this end we have developed a new animal model of massive pulmonary embolism. We are working collaboratively toward application of a bioabsorbable stent system to growing pulmonary and systemic arteries, which might represent a significant advance in the nonsurgical correction of various congenital cardiovascular diseases including pulmonary stenosis and aortic coarctation. NHLBI Cardiothoracic Surgery Research Branch investigators have used our interventional MRI system and environment to further test the feasibility and utility of real-time MRI guidance for surgical transapical implantation of a custom aortic stent valve bioprosthesis in swine. We have refined workflows, imaging techniques, and monitoring technology to prepare for first-in-man MRI-guided cardiac catheterization using an active MRI guidewire. This has required us also to develop a new infrastructure to conduct animal experiments according to Good Laboratory Practice. We expect a human test of our active guidewire in 2011. Overall we have successfully developed novel applications of real-time MRI for cardiovascular treatments. We continue to make progress to first human testing of this technology.